Studies On The Suzuki Coupling Catalyzed By Phosphine Adducts Of Cyclopalladated Ferrocenylimines

In this thesis, novel triphenylphosphine adducts 2-4 and tricyclohexylphosphine adductsl2&13of dimeric cyclopalladated ferrocenylimines were easily synthesized. 2-4 and 12&13 have been successfully used in palladium-catalyzed Suzuki cross-coupling of aryl bromides and aryl chlorides with phenylboronic acid, respectively.1. Ferrocenylimines 6 were synthesized by the condensation of formylferrocene or acetylferrocene with isopropylamine or cyclohexylamine. The reaction of ferrocenylimines 6 with Li2PdCl4 yielded dimeric cydopalladated ferrocenylimines 7, which was treated with PPh3 to produce triphenylphosphine adducts of dimeric cydopalladated ferrocenylimines 2-4. All the new compounds were characterized by EA (or HRMS), IR, ~1H NMR and ~31P NMR. The structure of 3 was determined by X-ray single crystal analysis.Scheme 12. The application of the catalysts 2-4 in the coupling of aryl bromides with phenylboronic acid were studied and we found that using 0.01 mol% of 3 aryl bromides and phenylboronic acid could be efficiently coupled. For activated bromides such as 4-bromonitrobenzene, the catalyst loadings could be lowered to3. Two novel tricyclohexylphosphine adducts of dimeric cyclopalladated ferrocenylimines 12 and 13 have been easily synthesized by treating the corresponding cyclopalladated ferrocenylimines la and 7b with PCy3. The new compounds were characterized by HRMS, IR, ~1H NMR and ~31P NMR. The structure of 12 was determined by X-ray single crystal analysis. Scheme 34. The novel tricyclohexylphosphine adducts of dimeric cyclopalladated ferrocenylimines 12 and 13 were successfully used in palladium-catalyzed Suzuki cross-coupling of aryl chlorides. Using 0.1 mol% of 13 in the presence of 2 equivalent of Cs2CO3 as base in dioxane at 100 ℃ provided coupled products in excellent yields in the reaction of non-activated and deactivated aryl chlorides with phenylboronic acid. For activated chlorides such as 4-chloronitrobenzene and 4-chloroacetophenone, the catalyst loadings could be lowered to 0.01 mol% without loss of activity.Scheme 4...